Synergistic herbicidal compositions comprising colletotrichum truncatum and chemical herbicides

ABSTRACT

Disclosed are compositions and processes for controlling undesirable weeds. These compositions comprise synergistic combinations of colletotrichumtruncatum and chemical herbicides. Use of the synergistic compositions of the subject invention enhances the value of the microbial herbicide by reducing the amount of microbial herbicide needed and by extending the range of environmental conditions in which the microbial herbicide will function.

The present application is a divisional application of co-pendingapplication Ser. No. 747,511, filed on June 21, 1985 now abandoned.

BACKGROUND OF THE INVENTION

Weeds cost farmers billions of dollars annually in crop losses and inthe expense of keeping the weeds under control. Much of the cost ofintertillage of row crops, maintenance of fallow, seedbed preparation,and seed cleaning is chargeable to weed control. Another expensive itemis suppression of weeds along highways and railroad right-of-ways, andin irrigation ditches, navigation channels, yards, parks, grounds, andhome gardens. Ragweed pollen is the source of annual periodic distressto several million hay fever sufferers. Poison ivy, poison oak, poisonsumac, nettles, thistles, sandburs, and puncturevine also bring pain tomillions. The barberry bush, which spreads the black-stem rust of grainsand grasses, can be regarded as a weed. Weeds also serve as hosts forother crop diseases as well as for insect pests.

The losses caused by weeds in agricultural production environmentsinclude decrease in crop yield, reduced crop quality, increasedirrigation costs, increased harvesting costs, decreased land value,injury to livestock, and crop damage from insects and diseases harboredby the weeds.

Chemical herbicides have provided an effective method of weed control inthe past. However, the public has become concerned about the amount ofchemicals applied to the food that they consume, to the land on whichthey live, and to the ground water which they use. Stringentrestrictions on the use and development of new herbicides and theelimination of some effective herbicides from the market place havelimited economical and effective means for controlling costly weedproblems.

A problem has been identified after years of use of chemical herbicideson commercial agricultural land, i.e., the lack of control of certainweeds has allowed these weeds to take over the areas where, without theuse of chemical herbicides, they were excluded by more hardy weeds.Removal of the more competitive weeds with chemical herbicides has leftan ecological void that has been filled by the less competitive weedsthat are resistant to the herbicides. Weeds that were of minorimportance at one time have spread rapidly throughout the areas wherethey are found and are now considered major weed problems. In additionto the inadequacy of control of all weeds, chemicals also can damage thecrop plants, sometimes injure nontarget organisms in the environment,and can leave undesirable residues in water and harvested products andcarry-over in subsequent crops.

Microbial herbicides are plant pathogens which are effective, when usedaccording to the process disclosed herein, in controlling weeds or otherundesirable vegetation without adversely affecting the growth and yieldof the desired field crop. The composition of a microbial herbicideincludes spores or cells of the plant pathogen or any portion of theorganism that is capable of infecting the weed. The use of microbialherbicides is becoming an increasingly important alternative to chemicalherbicides. This importance is accompanied by the issuance of severalpatents for microbial herbicides and their use. Some of these patents,by way of illustration, are as follows: U.S. Pat. No. 3,849,104 (controlof northern jointvetch with Collectotrichum gloeosporioides Penz.aeschynomene); U.S. Pat. No. 3,999,973 (control of prickly sida[teaweed] and other weeds with Collectotrichum malvarum); U.S. Pat. No.4,162,912 (control of milkweed vine with Araujia mosaic virus); U.S.Pat. No. 4,263,036 (control of Hydrilla verticillata with Fusariumroseum Culmorum); U.S. Pat. No. 4,390,360 (control of sicklepod, showycrotalaria, and coffee senna with Alternaria cassiae); and U.S. Pat. No.4,419,120 (control of prickly sida, velvetleaf, and spurred anoda withfungal pathogens).

Microbial herbicides have been developed specifically for control ofweeds which are not adequately controlled by chemical herbicides.Examples include Collectotrichum gloeosporioides f.sp. aeschynomene forcontrol of northern jointvetch in rice; Alternaria cassiae for controlof sicklepod in soybeans, cotton, and peanuts; and Fusarium lateritiumfor control of velvetleaf in soybeans. In each of these cases the weedis not effectively controlled by the chemical herbicides currentlylabeled for use in the respective cropping system. The factors currentlylimiting in commercialization of microbial herbicides are the high costof production, limited spectrum of weed control, and the narrow range ofenvironmental conditions in which these pathogens will infect the host.

The effects of herbicides on plant diseases was recently reviewed byAltman (Altman, J. and Campbell, L. C. [1977] Ann. Rev. Phytophathol.15:373-375). Altman reported that herbicides may either increase orreduce plant disease and severity. There are five major herbicideeffects which may lead to increased disease: (a) a reduction in thebiochemical defenses of the host against the pathogen; (b) reduction ofstructural defenses of the host; (c) stimulation of increased exudationfrom host plants; (d) stimulation of pathogen growth and/or productionof chemicals which damage the plant; and (e) inhibition of microfloracompeting with potential pathogens. There are four major effects ofherbicides which lead to decreased disease incidence and/or severity:(a) increased host biochemical defenses; (b) increased host structuraldefenses; (c) stimulation of microflora competing with potentialpathogens; and (d) a decrease in either the pathogen's growth or itsproduction of chemicals which are damaging to plants. At the currentstate of chemical herbicide and microbial herbicide art, there is nomethod of predicting the interaction (neutral, antagonistic, orsynergistic) between a microbial herbicide and a chemical herbicide incontrolling a specific weed or unwanted vegetation.

Prior art in the area of microbial herbicide and chemical herbicideinteractions indicates that foliar application of mixtures of amicrobial herbicide and a chemical herbicide results in antagonism andreduced efficacy of the microbial herbicide. Plant pathogens can breakdown chemical herbicides and chemical herbicides can be fungicidal(Wilson, C. L. [1969] Ann. Rev. Phytopathol. 7:424). Examples ofpositive interactions between microbial herbicides and chemicalherbicides require that the microbial herbicide be applied either beforeor after the application of the chemical herbicide (Klerk, R. A., Smith,Jr., R. J. and TeBeest, D. O. [1985] Weed Science 33:95-99). Multipleapplications of pest control products is expensive and commerciallyundesirable. The commercially viable methods for the application of acombination product (such as a microbial herbicide and a chemicalherbicide) are a "tank mix," and a "package mix." Tank mixing is aprocess by which two or more components of a pest control program areadded to the same spray tank and this mixture is applied to the field.The components may be packaged together (package mix) or separately(tank mix) but the components must be compatible when added to the spraytank. Mixtures are applied to the field with one application. Applying amixture reduces fuel consumption, machinery wear, and operator time; andpreserves the soil texture by reducing soil compaction. At this stage inthe herbicide art there is no known way to predict success, if any, incombining a chemical herbicide with a microbial herbicide.

We have discovered that mixtures of microbial herbicides and chemicalherbicides, and some chemical plant growth regulators, are synergisticin their activity when applied to the foliage of the host weed of themicrobial herbicide. This is the first report of synergy betweenmicrobial herbicides and chemical herbicides applied as mixtures. Thissynergy will greatly increase the value of microbial herbicides byreducing the amount of microbial herbicide applied, reducing theenvironmental limitations of the microbial herbicide, and increasing thespectrum of weed control of some herbicide treatments.

BRIEF SUMMARY OF THE INVENTION

The subject invention concerns the unexpected discovery that certainmixtures of microbial herbicides and chemical herbicides, and somechemical plant growth regulators, produce a synergistic effect againsttarget weeds. This synergistic effect significantly enhances the valueof the microbial herbicide by reducing the amount of microbial herbicideneeded and by extending the range of environmental conditions in whichthe microbial herbicide will function. Specifically, by using themicrobial herbicides and chemical herbicides disclosed herein, inmixture, there is obtained, advantageously, a synergistic effectresulting in kill or suppression of previously uncontrolled weeds orother vegetation.

The activity of a microbial herbicide is sensitive to fluctuations inthe environment. The majority of the examples which support ourdiscoveries were carried out under greenhouse conditions. Theenvironmental conditions within the greenhouse are more constant thanthe ambient environment outside the greenhouse. However, the environmentwithin the greenhouse fluctuates daily and the interaction between amicrobial herbicide and its host also varies with these changes inenvironment. The sensitivity of microbial herbicides to environmentalfluctuations is one of the major constraints in commercializing amicrobial herbicide. This sensitivity to environment explains the lackof consistent control when the same rate of microbial herbicide wasapplied to weeds on different days. This sensitivity to environment isreduced when the microbial herbicide is combined with a chemicalherbicide. The result is effective weed control under a wide range ofenvironmental conditions.

The discovery of microbial herbicides and chemical herbicides thatproduce a synergistic effect in controlling a target weed wasunexpected. Salts of chemical herbicides (which are organic acids) werediscovered to be synergistic when applied as mixtures with microbialherbicides. Not all salts of chemical herbicides demonstrated thissynergy with all microbial herbicides. However, all salts of chemicalherbicides which are active against broadleaf weeds (see Table 1) whenused with the microbial herbicides (which attack broadleaf weeds) werefound to be synergistic, and increase the spectrum of control of someherbicide treatments.

Generally, in the practice of the subject invention, the microbialherbicide can be applied at rates between 10E7 to 10E12 propagules peracres, and the chemical herbicide can be applied at rates of 1/2 to 1/32the rate recommended for weed control on the label of the compound inaccordance with EPA regulations, against the target weed. If desired,the chemical herbicides can be used at recommended full rates to achievea broader spectrum of weed control.

DETAILED DISCLOSURE OF THE INVENTION

The synergistic mixtures of microbial herbicides and chemical herbicidesof the subject invention make possible the control of weeds which cannotbe effectively controlled by either the microbial herbicide or thechemical herbicide alone. The most preferred microbial herbicides of theinvention are plant pathogens from the genera Alternaria,Collectotrichum, and Fusarium.

Other microbial herbicides of the invention include plant pathogens fromthe following genera:

    ______________________________________                                        Acremonium           Monochaeta                                               Ascochyta            Myrothecium                                              Bipolaris            Pestalotia                                               Cephalosporium       Phoma                                                    Ceratocystis         Phylosticta                                              Cercospora           Phytophthora                                             Coleosporium         Puccinia                                                 Curvularia           Septoria                                                 Dichotomophthora     Sphacelotheca                                            Dichotomophthoropsis Sporosporium                                             Dreschlera           Stemphylium                                              Exserohilum          Uredo                                                    Helminthosporium     Verticillium                                             ______________________________________                                    

Representative species and target weeds of the above genera are asfollows:

Acremonium diospyri (ATCC 22202,22206)

Weed: Diospyros virgianiana L. (persimmon)

Alternaria cassiae Jurair and Kahn (NRRL 12533, ATTC 4687)

Weed: Cassia obtusifolia L. (sicklepod)

Alternaria eichhorniae Nag Raj and Ponnappa (ATTC 22255)

Weed: Eichhornia crassipes (Mart.) Solms (water-hyacinth)

Alternaria helanthi (Hansford) Tugaki and Nishirara

Weed: Xanthium strumarium (heartleaf cocklebur)

Alternaria macrospora Zimm. (ATCC 42770)

Weed: Anoda cristata (L.) Schlecht. (spurred anoda)

Alternaria alternantherae Holcomb and Antonopoulos (ATCC 32833, 44528,48851)

Weed: Alternanthera philoxeroides (Mart.) Griseb. (alligatorweed)

Ascochyta pteridium Bres.

Weed: Pteridium aquilinum (bracken fern)

Ceratocystis fagacearum (Bretz) Hunt (ATCC 24790)

Tree: Quercus spp. (red and burr oak)

Cercospora hydrocotyles Ellis and Everh. (ATCC 36217)

Weed: Ipomoea hederacea (L.) Jacq. (morningglory, ivyleaf)

Cercospora nymphaeacea Cooke and Ellis (ATCC 36216)

Weed: Nuphar luteum (L.) Sibth. & Sm. (yellow waterlily)

Cercospora rodmanii Conway (U.S. Pat. No. 4,097,261)

Weed: Eichornia crassipes (Mart.) Solms. (water-hyacinth)

Colletotrichum coccodes Wallr. (DAOM 183088)

Weed: Abutilon theophrasti Medic. (velvetleaf)

Colletotrichum coccodes Wallr. (NRRL 15547)

Weed: Solanum ptycanthum (black nightshade)

Colletotrichum gloeosporioides (Penz.) f. sp. aeschynomene (ATCC 20358)

Weed: Aeschynomene virginica (L.) B.S.P. (northern jointvetch)

Colletotrichum gloeosporioides (Penz.) f. sp. jussiaeae (ATCC 52634)

Weed: Jussiaea decurrens (Walt.) DC. (winged primrose)

Colletotrichum malvarum (A. Braun and Casp) (NRRL 8096)

Weeds: Sida spinosa L. (prickly sida) Abutilon theophrasti Medic.(velvetleaf)

Colletotrichum truncatum (Schw.) Andrus & Moore (NRRL 15933)

Weed: Desmodium tortuosum (SW.) DC. (Florida beggarweed)

Dichotomophthora portulacae Mehrlich and Fitzpatrick (ATCC 22159)

Weed: Portulaca oleracea L. (common purslane)

Dichotomophthoropsis numphaerum (Rand) M. B. Ellis (ATCC 32819)

Weeds: Brasenia schreberi J. F. Gmel. (watershield) Nymphaea odorataAit. (fragrant waterlily)

Fusarium lateritium Nees ex Fr. (NRRL 12552)

Weeds: Anoda cristata (L.) Schlecht. (spurred anoda) Sida spinosa L.(prickly sida) Abutilon theophrasti Medic. (velvetleaf)

Fusarium oxysporum Schlect. f. sp. cannabis Noviello and Snyder (ATCC14838)

Weed: Cannabis sativa L. (hemp)

Fusarium oxysporum f. sp. perniciosum (Hept.) Toole (ATCC 12282)

Weed: Albizia julibrissin Durazz. (silktree albizia)

Fusarium solani App. & Wr. f. sp. cucurbitae Snyd. & Hans. (NRRL 52552)

Weed: Cucurbita texana (A.) Gray (Texas gourd)

Phytophthora palmivora (Butler) Butler (ATCC 52158, 52159)

Weed: Morrenia odorata Lindl. (stranglervine)

Puccinia canaliculata (Schw.) Lagerh.

Weed: Cyperus esculentus L. (yellow nutsedge)

Puccinia chondrillina

Weed: Chondrilla juncea L. (skeletonweed)

The microbial herbicides of the subject invention are known fungi, asdisclosed above. These fungi can be grown and formulated for use asmicrobial herbicides by procedure well known in the art. For example,the following is a list of disclosures giving growth characteristics forthe disclosed fungi: Alternaria macrospora Zimm. (ATCC 42770), seeWalker, H. L. (1979) Weed Sci. 27:612-614; Ascochyta pteridium Bres.,see TeBeest, D. O. and Templeton, G. E. (1985) Plant Disease 69:6-10;Colletotrichum gloeosporioides (Penz.) f. sp. aeschynomene (ATCC 20358),see Daniel, J. T., Templeton, G. E. and Smith Jr., J. (1974) U.S. Pat.No. 3,849,104; Colletotrichum malvarum (A. Braun and Casp) (NRRL 8096),see Templeton, G. E. (1976) U.S. Pat. No. 3,999,973; Fusarium lateritiumNees ex Fr. (NRRL 12552, see Walker, H. L. (1983) U.S. Pat. No.4,419,120; Fusarium solani App. & Wr. f. sp. cucurbitae Snyd. & Hans.(NRRL 52552), see Boyette, C. D., Templeton, G. E. and Oliver, L. R.(1984) Weed Sci. 32:649-655; Phytophthora palmivora (Butler) Butler(ATCC 52158, 52159), see TeBeest, D. O. and Templeton, G. E. (1985)Plant Disease (69:6-10; Puccinia chondrillina see Hasan, S. andWapshere, A. J. (1973) Ann. Appl Biol. 74:325-332; Puccinia canaliculata(Schw.) Lagerh., see Sutker, E. M. (1983) Phytopathology 73:506; andDichotomophthora portulaceae Mehrlich and Fitzpatrick (ATCC 22159), seeKlisiewicz, J. M. et al. (1983) Plant Disease 67:1162.

Four species from three genera, listed above, were selected to exemplifythis invention:

Alternaria cassiae

Colletotrichum coccodes

Colletotrichum truncatum

Fusarium lateritium

Listed in Table 1 are chemical herbicides which are salts of organicacids.

                  TABLE 1                                                         ______________________________________                                                                        Common                                        Trade Name.sup.1                                                                         Chemical Name        Name                                          ______________________________________                                        Alanap (B) 2-[(1-naphthalenylamino)carbonyl]                                                                  naptalam                                                 benzoic acid                                                       Basagran (B)                                                                             Sodium salt of (3-isopropyl-1                                                                      bentazon                                                 H--2,1,3-bentzothiadiazin-4                                                                        sodium                                                   (3H)--one 2,2-dioxide)                                                                             salt                                          Basta (B & G)                                                                            Ammonium-DL-homoalanin-4-yl                                                                        glufonsi-                                                (methyl) phosphinate nate                                                                          ammoni-                                                                       um                                            Blazer (B & G)                                                                           Sodium 5-[2-chloro-4-trifluoro                                                                     acifluor-                                                methyl)phenoxy]-2-nitrobenzoate                                                                    fen                                                                           sodium                                                                        salt                                          Butyrac 200 (B)                                                                          4-(2,4-Dichlorophenoxy)butyric                                                                     2,4-DB                                                   acid                                                               Cobra (B)  1-(carboethoxy)ethyl 5-[2-chloro-                                                                  lactofen                                                 4-(trifluoromethyl)phenoxy]-2-                                                nitrobenzoate                                                      DOWPON (G) 2,2'-dichloropropionic acid                                                                        dalapon                                       Fusilade (G)                                                                             Butyl(R-S)-2-[4-[[5-(trifluoro-                                                                    fluazifop                                                methyl)-2-pyridinyl]oxy]phenoxy]                                              propanoate                                                         Hoelon (G) Methyl 2-[4-(2,4-dichlorophenoxy)                                                                  diclofop                                                 phenoxy]propanoate   methyl                                        Premerge 3 Dinoseb(2-sec-butyl-4,6-dinitro-                                                                   dinoseb                                       (B & G)    phenol) as the alkanolamine                                                   salts                                                              Roundup (B & G)                                                                          Isopropylamine salt of N--                                                                         gly-                                                     (phosphonomethyl)glycine                                                                           phosate                                       Scepter (B)                                                                              Ammonium salt of 2-[4,5-Dihydro-                                                                   AC                                                       4-methyl ethyl)-5-oxo-1 .sub.--H--                                                                 252,214                                                  imidazol-2-yl]-3-quinoline                                                    carboxylic acid                                                    ______________________________________                                         .sup.1 The notation in parentheses indicates the activity of the herbicid     (B = broadleaf control, G = grass control, and B & G  broadleaf and grass     control.                                                                 

Table 2 lists chemical herbicides representing classes of herbicideswhich are not organic salts, but some having demonstrated a synergisticinteraction when used in combination with a microbial herbicide forcontrol of weeds.

                  TABLE 2                                                         ______________________________________                                        Trade name                                                                             Chemical Name       Common name                                      ______________________________________                                        Classic  2-(([(4-chloro-6-methox-                                                                          DPX-F6025                                                 pyrimidine-2-yl)amino carbonyl]                                               amino sulfonyl))benzoic acid                                                  ethyl ester                                                          Dual 8E  2-chloro-N--(2-ethyl-6-methyl-                                                                    metolachlor                                               phenyl)-N--(2-methoxy-1-methyl-                                               ethyl)acetamide                                                      Poast    2-[1-(ethoxyimino)butyl]-5[2-                                                                     sethoxydim                                                (ethylthio)propyl]-3-hydroxy-                                                 2-cyclohexen-1 one                                                   Sencor   4-Amino-6-(1,1-dimethylethyl)-                                                                    metribuzin                                                3-(methylthio)-1,2,4,-triazin-                                                5(4H)--one                                                           Surflan  3,5-Dinitro-N.sup.4 N.sup.4 --dipropyl-                                                           oryzalin                                                  sulfanilamide                                                        ______________________________________                                    

Table 3 discloses a plant growth regulators (PGR). Some havedemonstrated a synergistic interaction when used in combination with amicrobial herbicide for control of weeds.

                  TABLE 3                                                         ______________________________________                                        Trade Name                                                                             Chemical Name       Common Name                                      ______________________________________                                        B-Nine   Daminozide butanedioic acid                                                                       Alar                                                      mono(2,2-dimethylhydrazide)                                          Dropp    N--phenyl-N'--1,2,3-thiadiazol-                                                                   thidiazuron                                               5 yl urea                                                            Embark   Diethanolamine salt of (N--[2,4-                                                                  mefluidide                                                dimethyl-5-[[(trifluoromethyl)-                                               sulfonyl]amino]phenyl]acetamide                                      Stik     1-Naphthaleneacetic acid                                                                          NAA                                              ______________________________________                                    

The effect of chemical herbicides upon the germination or growth ofAlternaria cassiae (AC), Colletotrichum coccodes (CC), andColletotrichum truncatum (CT) was studied by exposing the fungi to thechemical or by amending the fungal growth medium with the chemicalherbicides. The concentration of herbicide in the medium was adjusted tobe equivalent to the concentration of herbicide which would be presentin the application spray tank when the herbicide is applied in 25 galwater per acre. Table 4 lists the low and high recommended rates ofapplication of each chemical used in this disclosure and thecorresponding concentration of the chemical (in parts per million [PPM])in the spray tank when the chemical is applied in 25 gal per acre.

Table 5 summarizes the results of spore germination studies with AC andCT. The fungi were exposed to the herbicides for about 8 hr at thereported concentration in water and then transferred to growth media todetermine germination. Percent difference indicates the magnitude andincrease or decrease in spore germination after exposure to thechemicals as compared to spores exposed to water only. The range ofresponse of CT (-91% to +27%) was greater than that of AC (-71% to+14%), indicating that CT may be more sensitive to the chemicals thanAC.

Table 6 summarizes the results of radial growth studies of CC on mediaamended with chemical herbicides. The concentration of chemicals in thegrowth medium was adjusted to equal the concentration of each herbicidein a spray tank when the chemical is applied in 25 gal water per acre.All of the treatments reduced the growth of CC over that of non-amendedmedium (range -8% to -82%).

                  TABLE 4                                                         ______________________________________                                        Concentration of herbicides and plant growth regulators                       in the application tank when the compounds are applied                        at a carrier rate of 25 gal/A                                                            Low rate  Conc.    High rate                                                                             Conc.                                   Chemical   (lb ai/A) (PPM)    (lb ai/A)                                                                             (PPM)                                   ______________________________________                                        Basagran   0.75      3599     1.00    4798                                    Blazer     0.40      1919     0.50    2399                                    Classic    0.02       96      0.17     816                                    Fusilade   0.25      1200     0.50    2399                                    Hoelon     0.50      2399     1.25    5998                                    Poast      0.10       480     0.50    2399                                    Scepter    0.10       480     0.23    1104                                    Sencor     0.25      1200     0.50    2399                                    Surflan    2.00      9596     4.00    19192                                   B-Nine (PGR)                                                                             0.50      2399     2.10    10076                                   Dropp (PGR)                                                                              0.10       480     0.20     960                                    Embark (PGR)                                                                             0.05       240     1.00    4798                                    ______________________________________                                         Note: One pound of active ingredient mixed into 25 gallons of water is        equivalent to 4798 ppm.                                                  

                  TABLE 5                                                         ______________________________________                                        The effect of chemical herbicides and plant growth                            regulators on the germination of spores of A. cassiae                         (AC) and C. truncatum (CT). The percentages represent                         the increased or decreased germination as compared to                         germination on plates which are not amended with the chemicals.                        Low rate                                                                             Conc.     Percent difference                                  Chemical   (lb ai/A)                                                                              (PPM)     AC      CT                                      ______________________________________                                        Basagran   0.75     3599      -15     -82                                     Blazer     0.40     1919       -6      -9                                     Classic    0.02      96       -19     -42                                     Fusilade   0.25     1200      +14     -25                                     Hoelon     0.50     2399      -71     -91                                     Poast      0.10      480      -24     NG                                      Scepter    0.10      480       +8     +27                                     Sencor     0.25     1200       +1     +11                                     Surflan    2.00     9596       +6     +13                                     B-Nine (PGR)                                                                             0.50     2399      +14     -12                                     Dropp (PGR)                                                                              0.10      480       -8      +2                                     Embark (PGR)                                                                             0.05      240      -11     -75                                     ______________________________________                                         Note: "NG" indicates that the spores did not germinate after exposure to      the chemical at the rate indicated above.                                

                  TABLE 6                                                         ______________________________________                                        Growth of C. coccodes on media amended with herbicides or                     plant growth regulators to a concentration equivalent to                      that encountered in a spray tank containing the low rate                      of the chemical and a carrier rate of 25 gal per acre.                        Colony diameter was measured after 12 days' incubation and                    is expressed as percent reduction in growth compared to                       growth on the medium without chemicals added.                                             Low rate           Percent                                        Chemical    (lb ai/A)   ppm    difference                                     ______________________________________                                        Basagran    0.75        3599   -23                                            Classic     0.02         96    -11                                            Dropp (PGR) 0.10         480    -8                                            Fusilade    0.25        1200   -43                                            Hoelon      0.50        2399   -82                                            Poast       0.10         480   -24                                            ______________________________________                                    

The three major steps in plant pathogenesis are germination,penetration, and establishment of the pathogen within the host.Germination and penetration are the most environmentally sensitivestages. The three genera of fungi used as examples in this disclosureare representative of two methods of penetration observed in plantpathogenic fungi. Fusarium and Alternaria spp. penetrate passivelythrough open stomates, lenticels, or wounds in the plant surface;Colletotrichum spp. penetrate in the plant surface; Colletotrichum spp.penetrate actively after formation of appressoria (specializedstructures which attach to the host surface and release enzymes whichdissolve the cuticle and wall materials, allowing penetration of theinfective hyphae) and through wounds in the plant surface. The possibleinteraction of chemical herbicides and the infection process of plantpathogenic fungi is discussed in the Examples.

The results of synergy experiments are summarized in Table 7. A detailedexplanation of each experiment is disclosed in the Examples whichfollow. Salts of chemical herbicides which are active against broadleafplants provided synergistic activity when applied in a mixture with themicrobial herbicide which is active on the broadleaf weed.

Basagran, Blazer, and Scepter are broadleaf chemical herbicides whichare salts of organic acids. These herbicides were synergistic with allof the microbial herbicides tested. Hoelon and Fusilade are also saltsof organic acids. Hoelon and Fusilade are active against grasses and notagainst broadleaf weeds or sedges. Hoelon does not have herbidicalactivity against broadleaf weeds and would therefore not be expected tobe synergistic when combined with a microbial herbicide active againstbroadleaf weeds. Hoelon is not synergistic when used in combination withC. truncatum for control of Florida beggarweed. Hoelon was,unexpectedly, synergistic with A. cassiae in control of sicklepod.Fusilade, on the other hand, was synergistic when combined with eitherA. cassiae or C. truncatum in control of their respective weed hosts.

                  TABLE 7                                                         ______________________________________                                                   Synergy with                                                       Chemical     AC     CC         CT   FL                                        ______________________________________                                        Basagran     +      +          +    +                                         Blazer       +      +          +    +                                         Classic      -      +          -                                              Fusilade     +                 +                                              Hoelon       +                 -                                              Poast        +                 -                                              Scepter      +                 +                                              Sencor       +                 -                                              Surflan      +                 +                                              Dropp (PGR)  -      +          +                                              B-Nine (PGR) -                 +                                              Embark (PGR) +                 +                                              ______________________________________                                    

The suppliers for the above chemical herbicides and plant growthregulators are as follows:

    ______________________________________                                        Trade Name       Supplier                                                     ______________________________________                                        Alanap           Uniroyal Chemical                                            Basagran         BASF Wyandotte Corp.                                         Basta            American Hoechst                                             Blazer           Rohm and Haas                                                B-Nine           Uniroyal Chemical                                            Butyrac 200      Union Carbide                                                Classic          Dupont                                                       Cobra            PPG Industries                                               DOWPON           Dow Chemical                                                 Dropp            NORAM                                                        Dual 8E          Ceiba Geigy                                                  Embark           3M                                                           Fusilade         ICI Americas Inc.                                            Hoelon           American Hoechst                                             Paraquat         Chevron                                                      Poast            BASF Wyandotte Corp.                                         Premerge 3       Dow Chemical                                                 Roundup          Monsanto                                                     Scepter          American Cyanimide                                           Sencor           Mobay Chemical                                               Stik             Union Carbide                                                Surflan          Elanco Products                                              ______________________________________                                    

The objective of formulating herbicides is to provide the correctcombination of ingredients so that the active component is suitable forapplication and optimum activity. Microbial herbicides have beenformulated as dusts, wettable powders, granules, and suspensions.

Wettable powder formulas of Colletotrichum, Alternaria, and Fusarium arecomposed of a diluent, wetting agent, and dispersant. Wetting agents anddispersants are surface active agents (surfactants) which reduce surfacetension and promote homogenous distribution during application. Acomprehensive list of surfactants is found in McCutcheon's Emulsifiers &Detergents 1985. Three to five percent of each is needed in the formulato insure performance of the microbial herbicide. The diluents modifythe formula to improve handling, storage, and application. Diluents thathave been mixed with microbial herbicides are clays (attapulgite,montmorilonite, kaolinite), non-phyllosilites (talc, diatomaceous earth,vermiculite, synthetic bulking agents) and botanicals (grain flours,ground plant parts).

The formulation and application of the chemical herbicides, disclosedherein, are well known to those skilled in the art. See HerbicideHandbook of the Weed Science Society of America, Fifth Edition, 1983.This handbook is published by Weed Science Society of America, 309 WestClark Street, Champaign, Ill. 61820. Also, instructions for theformulation and use of individual chemical herbicides are disclosed onthe product labels for the herbicides.

Several conventions are used in the following Examples to simplify thedata tables and discussions. Abbreviations are utilized to designate thelocation and type of trial (Loc-Type), the names of the microbialherbicides, and the names of the weeds. These abbreviations will bedescribed below.

Experiments are separated by location and type of trial. The locationabbreviations and corresponding description are: CA--California,FL--Florida, IL--Illinois, ML-Montreal, VT--Vermont. The control ofenvironment is indicated by the type of trial: C--controlled environmentgrowth chamber (highly controlled environment, temperature and light);G--greenhouse conditions (moderate control of temperature, littlecontrol of light); F--field conditions (no control of temperature,light, or relative humidity).

California: CA-G. All trials with this designation indicate that thetrial was conducted in California under greenhouse conditions. Weeds inthe cotyledonary stage of growth were treated in a precision applicationchamber designed specifically to test the efficacy of chemical andmicrobial herbicides. The application chamber utilizes carbon dioxide topressurize the test material. The test material is delivered to theplants through a standard flat fan spray nozzle (Tee Jet 8002, SprayingSystems Co., Wheaton, Ill.) at a carrier rate of 25 gal/A. Aftertreatment, the plants are placed into a mist chamber for 7 to 14 days.The percentage of plants which are dead or severely damaged (unlikely tosurvive) is recorded as percent weed control.

Florida: FL-F. The Florida field trial was carried out under permitsfrom the USDA and the State of Florida. The test materials were appliedin the morning and the trial was irrigated at dusk. Applications weremade with the aid of a field backpack sprayer calibrated to apply 25gal/A.

Illinois: IL-F. The Illinois field trial was carried out under permitsfrom the USDA and the state of Illinois. The test materials were appliedwith the aid of a field backpack sprayer calibrated to apply 50 gal/A.Plants were treated in the four leaf stage of growth.

Montreal: ML-C. Weeds in the cotyledon, one, or two leaf stage ofdevelopment were treated with solutions of test material to run-off. Therate of compounds in the spray solutions was based upon an applicationvolume of 100 gal/A. Inoculated plants were placed into a dew chamberfor 18 hr, then removed and placed in a controlled environment chamber.Evaluations were made after 20 to 45 days and the percentage of thetotal number of plants which were killed was recorded as percent weedcontrol.

Montreal: ML-G. Weeds in the cotyledon, one, or two leaf stage ofdevelopment were treated with solutions of test material to run-off. Therate of compounds in the spray solutions were based upon an applicationvolume of 100 gal/A. Inoculated plants were placed into a dew chamberfor 18 hr. then removed and placed in a controlled environment chamber.Evaluations were made after 20 to 45 days and the percentage of thetotal number of plants which were killed was recorded as percent weedcontrol.

Montreal: ML-F. Field grown weeds in the cotyledon, one, or two leafstage of development were treated with the test compounds in situ.Applications were made in a carrier volume of 100 gal/A. The percentageof the total number of plants which were killed was recorded as percentweed control.

Vermont: VT-F. Trials were applied using the same techniques describedin the Montreal field trials (ML-F).

The weed abbrevations listed below are those accepted and reported inthe Composite List of Weeds, Weed Science (1984) 2:Supp. 2.

ABUTH=Abutilon theophrasti Medik.

CASOB=Cassia obtusifolia L.

DEDTO=Desmodium tortuosum (Sw.) DC.

The abbreviations used for the microbial herbicides have been presentedpreviously but will be duplicated here.

AC=Alternaria cassiae

CC=Colletotrichum coccodes

CT=Colletotrichum truncatum

FL=Fusarium lateritium

Following are examples which illustrate the products and procedures,including the best mode, for practicing the invention. These examplesshould not be construed as limiting.

EXAMPLE 1 Basagran in Combination with AC, CC, CT, and FL

Basagran is a herbicide of broadleaf plants. This herbicide is a sodiumsalt of an organic acid. Basagran reduced the germination of spores ofAC and CT (Table 5) in addition to slowing the growth of CC (Table 6).Basagran produces synergistic activity in controlling weeds when mixedwith microbial herbicides, in spite of the apparent detrimental effectof this herbicide on the germination and growth of the microbialherbicides.

The weed control activity of AC and FL was zero when these microbialherbicides were applied alone in these experiments. This lack ofactivity indicates that the environmental conditions during theexperiment were restrictive to disease development. The activity of theAC and FL is greatly increased, even under these restrictiveenvironmental conditions, by addition of the chemical herbicide.

With regard to the tables in this Example and the Examples following,application rates for microbial herbicides are expressed as PPA(propagules per acre) ×10⁹. Application rates for chemicals areexpressedas pounds of active ingredient per acre.

    __________________________________________________________________________    Microbial  Trial Application Rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.57  0.05 0     0    86                                     CC    ABUTH                                                                              IL-F  4100.00                                                                             0.75 10    13   65                                     CC    ABUTH                                                                              ML-C  4100.00                                                                             0.30 67    8    92                                     CC    ABUTH                                                                              VT-F  4100.00                                                                             0.75 7     40   79                                     CT    DEDTO                                                                              CA-G  9.30  0.30 41    0    71                                     FL    ABUTH                                                                              CA-G  410.00                                                                              0.05 0     38   65                                     __________________________________________________________________________

The interaction reported in this Example was observed with a number ofchemical herbicides which are salts of organic acids. Salts of organicacids frequently act as buffers in biological systems by maintaining theconcentration of dissolved gasses and ions (e.g., the pH, which is thehydrogen ion concentration). A bicarbonate buffering system maintainsthe pH and CO₂ content of human blood plasma at the correct levels. Thebuffering capacity of organic acids and their salts is due to thedisassociation of the proton, metallic ion or other inorganic ions inaqueous solution. Salts of chemical herbicides are likely to act asbuffers whenever they occur in aqueous solution, and, more importantly,when they are mixed with microbial herbicides. In a chemically bufferedenvironment, the microbial herbicide may be able to infect the weed andcause disease under environmental conditions which would otherwise berestrictive.

In addition to the buffering capacity described above, salts of organicacids (the salt, the ionized acid, or the ion released by the salt) mayalso act on the plant or pathogen to produce the synergistic interactionobserved in this Example.

Salts of chemical herbicide compounds can be formed from metal cationsin combination with the herbicidally active anion. Preferred metalcations are alkali metal cations, for example, lithium, sodium,potassium, cessium, and rubidium; and alkaline earth metal cations, forexample, magnesium, calcium, strontium and barium. Other metal cationswhich can beused to form salts of chemical herbicide compounds are theheavy metal cations, for example, copper, silver, mercury, zinc,cadmium, chromium, manganese, iron, cobalt, nickel, aluminum, tin, andlead.

Salts of chemical herbicide compounds also can be formed from oniumcations, for example, ammonium cations, sulfonium and sufoxonium cationsand phosphonium cations.

In general, the subject invention includes any salt of an organic acidchemical herbicide compound. Advantageously, the salt form used shouldbe soluble or suspensible in the herbicidal formula mixture. Theformation ofsuch salts is well known to persons skilled in the chemicalherbicide art.

EXAMPLE 2 Blazer in Combination with AC, CC, CT, and FL

Blazer is another example of broadleaf chemical herbicide which is asalt of an organic acid. The environmental conditions during a majorityof the experiments was limiting and the microbial herbicidesdemonstrated little or no weed control activity on their respectivehosts. The inhibition of AC and CT spore germination and the reductionin growth of CC was much less than observed with the combinations withBasagran.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Mircrobial                                                                          Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.57  0.05 0     0    86                                     CC    ABUTH                                                                              VT-F  4100.00                                                                             0.40 7     43   62                                     CT    DEDTO                                                                              CA-G  9.3   0.05 0     0    94                                     FL    ABUTH                                                                              CA-G  410.00                                                                              0.05 0     0    20                                     __________________________________________________________________________

EXAMPLE 3 Classic in Combination with AC, CC, and CT

Classic is a broadleaf herbicide which is an ester. This herbicide isclearly antagonistic to the activity of AC when the mixture is appliedto control sicklepod. Classic does not severely inhibit the sporegerminationof AC, indicating that the antagonistic interactions ispossible affecting the physiology of the interaction between AC and thesicklepod plant. An example might indicate interference with stomatalopening which would makepenetration of AC into the leaf more difficult.

Classic is synergistic in controlling weeds when applied in combinationwith CC, or CT. Both of these fungi are capable of penetrating the leafdirectly (without the need for a wound or open stomates).

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.29  0.02 31    4    21                                     CC    ABUTH                                                                              ML-C  4100.00                                                                             0.01 0     0    58                                     CC    ABUTH                                                                              ML-F  4100.00                                                                             0.02 0     8    37                                     CT    DEDTO                                                                              FL-F  31.00 0.02 0     16   49                                     __________________________________________________________________________

EXAMPLE 4 Fusilade in Combination with AC and CT

Fusilade is a chemical herbicide which has activity in controllingmonocots. Fusilade is a salt of an organic acid. This formulation shouldyield some environmental buffering capacity. However, the synergisticactivity of this compound and AC and CT was not predictable. Fusiladewas stimulatory to germination of AC spores but inhibitory to spores ofCT (Table 5). Fusilade has no visible effect upon sicklepod or Floridabeggarweed when applied alone.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  1.5   0.08 21    8    100                                    CT    DEDTO                                                                              CA-G  9.3   0.06 0     21   100                                    __________________________________________________________________________

EXAMPLE 5 Hoelon in Combination with AC and CT

Hoelon is another chemical herbicide which has activity in controllingmonocot weeds. Like Fusilade, Hoelon is a salt of an organic acid.Unlike Fusilade, Hoelon almost completely inactivates CT as a microbialherbicideby preventing spore germination (Table 5). The nature of theinactivation (cidal or static) has not been determined. In contrast tothis interaction, AC demonstrates a synergistic response in controllingsicklepod when applied in combination with Hoelon.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.57  0.25 0     4    61                                     CT    DEDTO                                                                              CA-G  9.3   0.25 0     0    0                                      __________________________________________________________________________

EXAMPLE 6 Poast in Combinatio with AC and CT

Poast, another monocot herbicide, is a ketone. The interaction of thisherbicide with AC for control of sicklepod is dramatic. Neither thefungusnor the chemical demonstrated any control when applied alone.Poast may be capable of stabilizing the environment, modifying thephysiology of the fungus, modifying the response of the host, or thepathogen was capable ofmodifying the activity of the herbicide.

Poast considerably reduced the germination of AC spores. The spores ofCT were completely inhibited. The response of CT spores to Hoelon andPoast is similar.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.57  0.05 0     0    100                                    CT    DEDTO                                                                              CA-G  9.3   0.01 7     0    18                                     __________________________________________________________________________

EXAMPLE 7 Scepter in Combination with AC and CT

Scepter, a broadleaf herbicide, is a salt of an organic acid. Refer toExample 1 for a discussion of the possible interactions betweenmicrobial herbicides and salts of chemical herbicides. Scepter alone hassome herbicidal activity against sicklepod. However, the combination ofthe microbial and chemical herbicides provides greatly enhanced,synergistic, control of sicklepod. The activity of CT and Scepter forcontrol of Florida beggarweed is not as dramatic as that demonstratedwith AC. Neither the CT nor Scepter were capable of damaging Floridabeggarweed alone. The combination killed one third of the weeds.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.29  0.01 31    17   76                                     CT    DEDTO                                                                              CA-G  31.00 0.15 0     0    33                                     __________________________________________________________________________

EXAMPLE 8 Sencor in Combination with AC and CT

Sencor and Surflan (Example 9) are non-selective herbicides which arenormally applied to fields as a preplant treatment. Sencor and Surflancannot be applied as post emergence herbicides because they arephytotoxicto most field crops at the rates needed to eliminate theweeds. The interaction between these herbicides and microbial herbicidesin controlling weeds is probably a result of increased exudation by thehost.Sencor and Surflan will damage some of the cells of the sicklepodwhen applied at the low rates used in Examples 8 and 9. However, thisdamage isnot enough to significantly reduce the growth and developmentof sicklepod.The damage is enough to cause cuticular wounds and leakageof cellular contents. This increase in exudation (actually uncontrolledrelease) provides extra nutrition for the fungus and increases its rateof growth. In addition to the increase of growth and activity of thefungus, the plant has been damaged and is therefore crippled in itsability to defend against the fungal invasion.

The chemical herbicide Paraquat is another non-selective herbicide. Thisherbicide is known to damage the plant cuticle. If the trend ininteractions presented in this disclosure is maintained with furthertesting, this herbicide should provide a combination of cuticular damagein addition to its biological buffering capabilities. The interactionshould be synergistic.

Also note that both of these compounds stimulated the germination of ACandCT spores (Table 5).

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  1.10  0.06 0     29   100                                    CT    DEDTO                                                                              CA-G  9.3   0.03 7     92   82                                     __________________________________________________________________________

EXAMPLE 9Surflan in combination with AC and CT.

Refer to the discussion of EXAMPLE 8 for an interpretation of theresults in this Table.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  1.5   2.60 21    14   75                                     CT    DEDTO                                                                              CA-G  9.3   0.50 0     13   100                                    __________________________________________________________________________

EXAMPLE 10 Plant Growth Regulator B-Nine in Combination wih AC and CT

The plant growth regulators (PGR) B-Nine and Dropp (Example 11) wereneither synergistic nor antagonistic when applied in combination withAC. However, both of these PGR's demonstrated synergy when applied witha Colletotrichum sp. (CC and CT). The compounds may be affecting thefungi to make them more aggressive, or inducing the host to become moresusceptible (by interference with the host physical and biochemicaldefenses). Both of these PGR's tend to make the plant short and growabnormally.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  0.57  0.05 0     0    7                                      CT    DEDTO                                                                              CA-G  42.00 0.40 23    63   100                                    __________________________________________________________________________

EXAMPLE 11 Plant Growth Regulator Dropp in Combination with AC, CC, andCT

Refer to Example 10 for a discussion of the activity of this compound.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  1.10  0.10 0     0    0                                      CC    ABUTH                                                                              ML-C  4100.00                                                                             0.07 0     0    42                                     CC    ABUTH                                                                              ML-C  4100.00                                                                             0.14 17    0    67                                     CC    ABUTH                                                                              ML-G  4100.00                                                                             0.07 0     0    67                                     CT    DEDTO                                                                              CA-G  9.3   0.03 23    42   100                                    __________________________________________________________________________

EXAMPLE 12 Plant Growth Regulator Embark in Comination with AC and CT

Embark is a plant growth regulator which demonstrates synergy whenapplied in combination with AC and CT. Unlike B-Nine and Dropp (Examples10 and 11) Embark is a salt of an organic acid. Refer to Example 1 for adiscussion of the possible interactions of organic salts and microbialherbicides.

    __________________________________________________________________________    Microbial  Trial Application rate                                                                         Percent weed control                              Herbicide                                                                           Weed Loc-Type                                                                            Microbial                                                                           Chemical                                                                           Microbial                                                                           Chemical                                                                           Tank mix                               __________________________________________________________________________    AC    CASOB                                                                              CA-G  1.1   0.05 0     0    73                                     CT    DEDTO                                                                              CA-G  9.3   0.25 23    0    100                                    __________________________________________________________________________

EXAMPLE 13

C. malvarum, disclosed in U.S. Pat. No. 3,999,973, can be used incombination with a chemical herbicide or plant growth regulator, asdisclosed herein, to control the growth of prickly sida (Sida spinosaL.) or teaweed.

EXAMPLE 14

Fusarium lateritium, disclosed in U.S. Pat. No. 4,419,120, can be usedin combination with a chemical herbicide or plant growth regulator, asdisclosed herein, to control the growth of prickly sida, velvet-leaf,and spurred anoda.

EXAMPLE 15

C. gloeosporioides f. sp. aeschynomene, disclosed in U.S. Pat. No.3,849,104, can be used in combination with a chemical herbicide or plantgrowth regulator, as disclosed herein, to control the growth of northernjointvetch.

EXAMPLE 16

Upon using a mixture of two or more chemical herbicides or plant growthregulators, as disclosed herein, in a mixture with a microbial herbicidewhich is a plant pathogen for a target weed, as disclosed herein, thereisobtained multiple weed control.

The Examples presented herein show synergy with salts of chemicalherbicides and plant growth regulators in mixture with microbialherbicides where the salt is compatible with the microbial herbicide.

We claim:
 1. A composition for controlling Florida beggarweed comprisingan effecive amount of the fungal pathogen Colletotrichum truncatum, anda chemical herbicide selected from the group consisting of bentazonsodium salt, acifluorfen sodium salt, fluazifop, and oryzalin.
 2. Thecomposition according to claim 1 wherein the chemical herbicide isbentazon sodium salt.
 3. The composition according to claim 1 whereinthe chemical herbicide is acifluorfen sodium salt.
 4. The compositionaccording to claim 1 wherein the claimed herbicide is fluazifop.
 5. Thecomposition according to claim 1 wherein the chemical herbicide isoryzalin.
 6. A process for controlling Florida beggarweed comprising theapplication of an effective amount of a synergistic herbidicalcomposition of Colletotrichum truncatum, and a chemical herbicideselected from the group consisting of bentazon sodium salt, acifluorfensodium salt, fluazifop, and oryzalin.
 7. The process of claim 6 whereinthe chemical herbicide is bentazon sodium salt.
 8. The process of claim6 wherein the chemical herbicide is acifluorfen sodium salt.
 9. Theprocess of claim 6 wherein the chemical herbicide is fluazifop.
 10. Theprocess of claim 6 wherein the chemical herbicide is oryzalin.